The primary goal of the proposed project is the rigorous testing of a formal model of fertility-related decision making. The model specifies how individuals combine beliefs about the consequences of fertility behaviors with evaluations of those consequences to make decisions. The model will be tested for individuals and couples in three experiments, each focusing on a different fertility-related decision. The three decisions to be investigated are a) choice of contraceptive method, b) time inerval between marriage and birth of the first child, and c) time interval between the first and second children. Each experiment will include a test of the model for each individual, identification of the sources of any deviations from the model, and identification of important sources of individual differences. The hypothesis that each couple's joint decisions can be predicted from a weighted combination of the individual decisions will be tested in each experiment, and within-couple measures of the relative impact of each spouse on the joint decision will be developed. All experiments will use the methods of psychological measurement theory.